A. Field of the Invention
The present invention relates to a variable camber airfoil, and more particularly to an apparatus particularly adapted to vary the camber of the trailing edge portion of an airfoil.
B. Brief Description of the Prior Art
A common way of modifying the lift characteristics of an airfoil for low speed operation is to use leading edge and trailing edge devices which either pivot or slide outwardly from the airfoil to a deployed position. With many such devices, there is the problem that during deployment, there is an interruption in smooth air flow over the airfoil. Also, many of these devices are not able to be deployed to intermediate positions while maintaining the proper flow of air over the airfoil. Accordingly, there have appeared in the prior art various devices to vary the shape of the airfoil itself in a manner to change the camber and thus modify its lift characteristics.
U.S. Pat. No. 4,131,253, Zapel, illustrates a trailing edge flap where there is a walking beam positioned between upper and lower variable camber skin sections, and comprises a forward positioning section and a rearwardly extending locating arm. The positioning section is connected to the lower swing ends of two pivot links which extend upwardly and convergently toward one another to connect with a fixed frame at spaced locations so that forward or rearward movement of the positioning section causes a locating arm of the walking beam to rotate, respectively, downwardly or upwardly. A trailing edge beam is connected by its forward end to the support frame, and by its rear end to the trailing edge end section, with the trailing edge beam being connected at an intermediate portion thereof to the rear end of the locating arm of the walking beam. Thus, downward or upward rotational movement of the locating arm of the walking beam causes a corresponding downward or upward rotational movement of the trailing edge end section of a correspondingly greater degree of rotation, relative to the locating arm.
It is an object of the present invention to provide a variable camber airfoil, where a relatively high degree of deflection can be obtained, by linkage positioned within a relatively small operating envelope in the wing.